1. Field of the Invention
The invention relates to power driven conveyors of the type having a continuous rubber belt formed with convolutions separating the belt into individual compartments. Specifically, the invention is a loading station for such a conveyor belt wherein the convolutions of the belt are temporarily reduced in size or eliminated to facilitate the loading of granular material, particularly explosives.
2. Description of the Prior Art
Flexible conveyors capable of following a curved path have been known, as evidenced by U.S. Pat. No. 2,701,050 to Steinborn, which is the counterpart of an original German patent application. Later developments in such conveyor construction are seen in U.S. Pat. No. 2,836,283 to Horth and U.S. Pat. No. 3,169,631 to Knappe. Other patents related to such conveyors include U.S. Pat. No. 3,920,115 to Craggs and U.S. Pat. No. 3,707,218 to Payne. Conveyors manufactured in accordance with the above patents may be described as flexible, segmented trough belt conveyors wherein the belt on the conveyor consists of semi-rigid, reinforced corrugated rubber segments bolted together to form any belt length. Every fifth belt segment is bolted to a carriage that rides on rubber tires, and the tires are adapted to follow a track that defines the desired path for the conveyor. The carriages are connected to each other by a link chain, which in turn is driven to drive the entire conveyor.
As can be understood from the above description, the several carriages connected by link chain are capable of bending in curves or deforming in valleys or over peaks without difficulty. The corrugated nature of the belt enables it to stretch over peaks and compress in valleys, and stretch and compress as necessary on horizontal turns.
At the end of each run of the conveyor, the belt passes around an end sprocket and becomes inverted for the return trip to the start of the run. As the belt makes the required 180 degree inversion, the corrugations are known to be stretched almost to the point of total elimination, with the result that the belt is very close to being smooth. In the past, this point in the belt travel has offered the greatest opportunity to clean the belt by applying a scraper or other cleaning device to the belt surface, since the corrugations will not be present to disrupt the operation of the cleaning device.
The stretching of a belt passing around a sprocket has been employed in other arts for useful purposes. U.S. Pat. No. 3,741,372 to Hewett utilizes a belt with interior compartments that are closed when the belt is flat, but that have an external opening exposed when the belt is stretched, as when the belt is passing around an end pulley. Hewett uses the belt as a pick-up and discharge device wherein material is received at one end of the conveyor run and discharged at the opposite end. This same concept is found in other U.S. patents, including U.S. Pat. Nos. 810,510 to Robins; 2,988,199 to Pinkham; 3,342,310 to Gray; 3,750,864 to Nolte; and 4,019,625 to Wiese. It is known from these various teachings that the stretching of a belt at the end sprocket of a conveyor run will flatten corrugations or open interior cavities in the belt. This knowledge has been employed to fill or empty the cavities or to clean the belt at the end-of-run sprocket, as noted above.
The problem addressed in the present invention is that certain materials are dangerous and difficult to handle, particularly in those instances where the materials will be subjected to friction. One such material is explosive powder such as gun powder. When an explosive powder is to be loaded on a conveyor, it is desirable that the powder be accurately contained in such a way that none of the powder will spill. Any spillage may potentially fall into machinery where it could be accidentally ignited, or it may simply constitute a hazardous accumulation of dangerous material.
Another goal of powder transport is that the material be physically isolated in relatively small amounts so that if accidental ignition or explosion should occur, the loss may be confined.
An overall goal is that friction be minimized so that the powder is not exposed to conditions likely to cause ignition or explosion.
In the past, these objectives have not been addressed. The present invention employs a flexible conveyor belt plus suitable support structure to create a unique loading station for explosive powders wherein the powders are handled with a minimum of friction while achieving all of the above goals.